1. Field of the Invention
The present invention relates to 2-alkoxycarbonyl-4-(4-pyridyl)cyclohexanones and a process for preparing them. 2-Alkoxycarbonyl-4-(4-pyridyl)cyclohexanones are important intermediates of agricultural chemicals and medicines, in particular for preparing isoquinoline derivatives which are in turn useful as medicines.
2. Description of the Prior Art
2-Carboxylic acids of cyclohexanone derivatives having a substituent at 4-position have been known: see D. Y. Curtin, J.A.C.S., 1960, 82, 2357. such carboxylic acids having a phenyl substituent at 4-position can be esterified to produce 2-alkoxycarbonyl-4-phenylcyclohexanones. However, 2-alkoxycarbonyl-4-(4-pyridyl)-cyclohexanones, which are objects of the present invention, have not been known at all.
According to the prior art referred to hereinabove, the 2-alkoxycarbonyl-4-phenylcyclohexanones are prepared by first providing 4-phenylcyclohexanones and then introducing a carboxyl group into 2-position.
Thus, if 2-alkoxycarbonyl-34-(4-pyridyl)cyclohexanones of the present invention are to be prepared according to the conventional technique, then 4-(4-pyridyl)cyclohexanones must be first provided. However, the 4-(4-pyridyl)cyclohexanones themselves are unknown compounds and, accordingly, this problem of preparing novel 2-alkoxycarbonyl-4-(4-pyridyl)cyclohexanones cannot be solved by application of the conventional process.